Carb Adjustment

[Jimford]

I put my e-series on w/uni filter. I jetted 40 pilot, mooved needle up and works great. Bottom- midrange is perfect. In 1st and 2nd gear top end, it sputters like I have to go up in main jett size. But in 3rd gear and up it seems fine. Can I adjust the carb or should I just go up one more size main. What a pain in the *** taking the front fenders apart. I appreciate any help thanks.

[cals400ex]

i have a feeling your just hitting the rev limiter.
what size mainjet are you running and is it keihin or dynojets?

also, for changing the mainjet, don't take everything apart. on the bottom of the carb there is a big bolt (17mm). just unskrew that with a socket and the mainjet is right in there. the mainjet is 6mm. just remember to not put the mainjet in there too tight or you may have problems unskrewing the needle jet holder along with the mainjet next time you try to take the main out. when this happnes it is just best to take the whole carb off and start over. when changing the pilot jet i think it is best to take the whole carb off. by the way, you don't even need to take the front fenders off when changing the mainjet. you can just pull the black plastic pieces off and and slide the gas tank out without even removing the bolts that hold the front fenders in place.

good luck

[Jimford]

I have a 99 400ex. I am running a 155 main jet. keihin. I don't think I am hitting the rev limiter. I might sound like I don't know anything but the truth is that I've been working on small engines and cars my whole life. Jetting is new to me. But I'm getting better at it. I thought the 155 would work fine. But since I know my quad I can tell I'm knowwhere near the rev limit. Ya know what I mean? What is the next size up 160? Thanks for the info on the bolt on the bottom. I remember on all my old dirtbikes that they had the same thing. It is REALLY COLD here in Buffalo. -10 windchill some times! Could that be it? Another thing, I never had to rejet in the winter or summer with my stock exhaust. Will I have to in summer also? Thanks so much Brotha!

[cals400ex]

you won't have to rejet in both summer and winter but i do since i am anal about jetting. a 155 keihin main would be the exact size i would put in if i were you.
your running the airbox lid on aren't you? and i assume the pipe and filter are your only mods?
they do make a 158 keihin mainjet and a 160. i wouldn't put in a 160 for sure. the richer you go (larger jets) the less power it will have unless you need the extra fuel. you could try a 158 but i dont' think that is your problem. the rev limiter is honestly the only thing i can think of. it will be much harder to hit it in third than it would be in 1st or 2nd. but, if you know for a fact it isn't the rev limiter, i am stumped. :confused:

if the mainjet was wrong by a lot, it would spudder in all of the gears and not just the first two. however, i find the mainjet needs to be off quite a bit for the bike to spudder. i honestly don't think its your jetting. i guess you could try to get a new plug and make sure it is in the head tight. i think the torque is 13 ft/lbs for the plug.